Madison County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 16,548. The county seat is Winterset. Madison County is included in the Des Moines–West Des Moines, IA Metropolitan Statistical Area. Madison County is famous for being the county where John Wayne was born, and for a number of covered bridges. These bridges were featured in Robert James Waller's 1992 novella The Bridges of Madison County, as well as the 1995 film and 2014 musical based on it.